I have good news for you, at least as far as ReadOnly is concerned there already is a PEP: PEP 767: Annotating Read-Only Attributes
Expanding Required/NotRequired to protocols has also already come up a few times, but nobody went as far as writing a PEP for that yet and there seems to be overall less of an appetite for it.
That being said, I do agree that it makes perfect sense to expand those qualifiers to work in Protocol, since both TypedDict and Protocol are structural types. Someone just has to be willing to put in the required work to advance the proposal beyond just an ideas thread.